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Date:      Mon, 15 Jan 2018 21:52:44 -0600
From:      Alan Cox <alc@rice.edu>
To:        Nathan Whitehorn <nwhitehorn@freebsd.org>, Konstantin Belousov <kostikbel@gmail.com>
Cc:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Re: svn commit: r327950 - in head/sys/powerpc: aim include powerpc ps3
Message-ID:  <7ec31517-8488-dd93-fa30-3400f6a4d562@rice.edu>
In-Reply-To: <bcae7547-713b-0e5e-6302-af48d7dcbcde@freebsd.org>
References:  <20180114175211.GD1684@kib.kiev.ua> <b2b1bf30-177b-af30-54ce-f484224bb2ad@freebsd.org> <f4b44b69-7b06-6b5a-c17c-31bd46ca1af0@freebsd.org> <e04bc7a6-fa77-9ca0-2aff-dc29c543c9a1@freebsd.org> <20180115111812.GF1684@kib.kiev.ua> <f6350c61-55d1-9bf7-c4b3-e10fb329a42a@freebsd.org> <20180115170603.GJ1684@kib.kiev.ua> <9e5554d7-6a0c-5910-8cb6-74f98259536f@freebsd.org> <20180115175335.GK1684@kib.kiev.ua> <bb27ba01-8383-6b85-8b2b-65227ff46efc@freebsd.org> <20180115234218.GN1684@kib.kiev.ua> <bcae7547-713b-0e5e-6302-af48d7dcbcde@freebsd.org>

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On 01/15/2018 20:40, Nathan Whitehorn wrote:
>
>
> On 01/15/18 15:42, Konstantin Belousov wrote:
>> On Mon, Jan 15, 2018 at 03:20:49PM -0800, Nathan Whitehorn wrote:
>>> Fair enough. Here's a patch with a new flag (DIRECT_MAP_AVAILABLE).
>>> I've
>>> also retooled the sfbuf code to use this rather than its own flags that
>>> mean the same things. The sparc64 part of the patch is untested.
>>> -Nathan
>>> Index: amd64/include/vmparam.h
>>> ===================================================================
>>> --- amd64/include/vmparam.h    (revision 328006)
>>> +++ amd64/include/vmparam.h    (working copy)
>>> @@ -190,6 +190,7 @@
>>>    * because the result is not actually accessed until later, but
>>> the early
>>>    * vt fb startup needs to be reworked.
>>>    */
>>> +#define    DIRECT_MAP_AVAILABLE    1
>>>   #define    PHYS_TO_DMAP(x)    ({                        \
>>>       KASSERT(dmaplimit == 0 || (x) < dmaplimit,            \
>>>           ("physical address %#jx not covered by the DMAP",        \
>>> Index: arm64/include/vmparam.h
>>> ===================================================================
>>> --- arm64/include/vmparam.h    (revision 328006)
>>> +++ arm64/include/vmparam.h    (working copy)
>>> @@ -176,6 +176,7 @@
>>>   #define    VIRT_IN_DMAP(va)    ((va) >= DMAP_MIN_ADDRESS && \
>>>       (va) < (dmap_max_addr))
>>>   +#define    DIRECT_MAP_AVAILABLE
>> Just define, or define it to 1 ?
>
> Yes, sorry for typo.
>
>>
>>>   #define    PHYS_TO_DMAP(pa)                        \
>>>   ({                                    \
>>>       KASSERT(PHYS_IN_DMAP(pa),                    \
>>> Index: dev/efidev/efirt.c
>>> ===================================================================
>>> --- dev/efidev/efirt.c    (revision 328006)
>>> +++ dev/efidev/efirt.c    (working copy)
>>> @@ -115,6 +115,11 @@
>>>           return (0);
>>>       }
>>>       efi_systbl = (struct efi_systbl *)PHYS_TO_DMAP(efi_systbl_phys);
>>> +    if (efi_systbl == NULL) {
>>> +        if (bootverbose)
>>> +            printf("EFI systbl not mapped in kernel VA\n");
>>> +        return (0);
>>> +    }
>> Is this chunk still needed ?
>
> The existing code is a bit of an awkward superposition of the "return
> NULL" idea and having the flag. Since you think there will never be
> intermediate cases -- which seems reasonable -- I will rip the
> conditional logic out and add a KASSERT matching the ones on arm64 and
> amd64 to the powerpc version.
>
>>
>>>       if (efi_systbl->st_hdr.th_sig != EFI_SYSTBL_SIG) {
>>>           efi_systbl = NULL;
>>>           if (bootverbose)
>>> Index: kern/subr_sfbuf.c
>>> ===================================================================
>>> --- kern/subr_sfbuf.c    (revision 328006)
>>> +++ kern/subr_sfbuf.c    (working copy)
>>> @@ -88,8 +88,8 @@
>>>       vm_offset_t sf_base;
>>>       int i;
>>>   -#ifdef SFBUF_OPTIONAL_DIRECT_MAP
>>> -    if (SFBUF_OPTIONAL_DIRECT_MAP)
>>> +#ifdef DIRECT_MAP_AVAILABLE
>>> +    if (DIRECT_MAP_AVAILABLE)
>>>           return;
>> Would it make sense to define the symbol on all other arches as 0 then,
>> and remove #ifdef ? Returning to your initial proposal of relying on the
>> compiler optimiing if (0) block; out.
>
> That is a good idea.
>
>> Also, just curious, why did you spelled DMAP as DIRECT_MAP ?
>>
>
> DMAP without the PHYS_TO_ seemed lacking in context and I was worried
> there might be a collision on DMAP. PMAP_HAS_DMAP would also work; I
> don't have a preference.
>

I would suggest "ARCH_HAS_DMAP".





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